Zika virus-like particles bearing covalent dimer of envelope protein protect mice from lethal challenge

Abstract

<jats:p>Zika virus (ZIKV) envelope (E) protein is the major target of neutralizing antibodies in infected host, and thus represents a candidate of interest for vaccine design. However, a major concern in the development of vaccines against ZIKV and the related dengue virus is the induction of cross-reactive poorly neutralizing antibodies that can cause antibody-dependent enhancement (ADE) of infection. This risk necessitates particular care in vaccine design. Specifically, the engineered immunogens should have their cross-reactive epitopes masked, and they should be optimized for eliciting virus-specific strongly neutralizing antibodies upon vaccination. Here, we developed ZIKV subunit- and virus-like particle (VLP)-based vaccines displaying E in its wild type form, or E locked in a covalently linked dimeric (cvD) conformation to enhance the exposure of E dimers to the immune system. Compared with their wild-type derivatives, cvD immunogens elicited antibody with higher capacity of neutralizing virus infection of cultured cells. More importantly, these immunogens protected animals from lethal challenge with both the African and Asian lineages of ZIKV, impairing virus dissemination to brain and sexual organs. Moreover, the locked conformation of E reduced the exposure of epitopes recognized by cross-reactive antibodies and therefore showed a lower potential to induce ADE in vitro. Our data demonstrated a higher efficacy of the VLPs in comparison with the soluble dimer and support VLP-cvD as a promising ZIKV vaccine.</jats:p>

Validation of an engineered Zika virus-like particle vaccine candidate in a mosquito-mouse transmission model

“…The lack of a visible manifestation of symptoms in A129 mice after infection with ZIKV PRVABC59 was unexpected since this strain is commonly used in ZIKV laboratory animal challenge models, usually with reported development of symptoms after an average infection with 10 4 pfu by subcutaneous injection (7,33). A similar lack of development of clinical symptoms and lethality was also observed in A129 mice during the initial preliminary infection performed to set up the mosquito-mouse infection model (Sup IFNα/βR-/-mice (A129), likely due to the enhanced immunodeficiency of the former strain.…”

“…During the past few years, several candidate vaccines have been developed and tested in preclinical stages (7)(8)(9) and the most promising ones have now moved to clinical trials (10,11). Preclinical tests for ZIKV vaccine candidates are performed on murine or nonhuman primate (NHP) models.…”

“…We previously reported a candidate vaccine comprising ZIKV virus-like particles (VLPs) that have been engineered to display the viral envelope (E) protein locked into a stable dimeric conformation via a disulphide bridge (VLP-cvD) (7). This vaccine conferred protection against both Asian (PRVABC59) and African (MP1751) lineages of ZIKV in a mouse model through the generation of strongly neutralizing antibodies and dramatically reduced virus dissemination to organs, such as brain and testis.…”

“…albopictus C6/36 cells: the infected supernatant was harvested, concentrated using Amicon Ultra-15 filters (Millipore, IRL), and titrated via fluorescent focus assay (FFA), as described below. ZIKV PRVABC59 (kindly supplied by BEI Resources; accession number KX087101) and ZIKV MP1751 (005V-02871; kindly supplied by Public Health England; accession number KY288905.1) were used for micro-neutralization, mosquito injections and animal challenges.VLP-cvD production and purification: VLP-cvD were produced in Expi293F cells at 28°Cfollowing transfection with a plasmid expressing ZIKV prM-E-A264C and purified as described in De Lorenzo et al (2020)(7) by performing, in sequence, 20% sucrose cushion, discontinuous 10-30% sodium potassium tartrate density gradient and size-exclusion chromatography with elution in PBS buffer. Eluted fractions were concentrated by ultrafiltration through Amicon® Ultra 15 (100 kDa, Merk Millipore).Mouse immunisation and ZIKV challenge: A129 mice or AG129KO mice (129Sv/Ev background; Marshall BioResources) at 4 weeks of age were immunised subcutaneously with either VLP-cvD or PBS, both adjuvanted with 1% AddaVax (InvivoGen).…”

Congenital Deafness and Recent Advances Towards Restoring Hearing Loss

“…Another explanation could be the presence of different strains of ZIKV with different levels of aggressiveness (Russo, Jungmann, & Beltrao‐Braga, 2017). Several vaccines and antiviral peptide therapies have been developed, and some vaccine candidates are currently in phase I of clinical trials to protect the population against the Zika virus (Camargos et al., 2019; De Lorenzo et al., 2020; Trovato, Sartorius, D'Apice, Manco, & De Berardinis, 2020).…”